The building and construction (B&C) industry uses fabrics, polymer films, and other such sheet-like materials extensively to cushion, insulate, seal, or protect the various components of a building as it is being constructed. Examples of these sheet-like materials include housewrap, lumber wrap, roof underpayment, flashing, etc. These materials should be tough and strong to withstand the rigors of the building process. These materials often need to be water repellant, to protect the interior of the building from moisture damage. It may be desirable to have these sheet-like materials be breathable, in order to allow water vapor generated in the building to escape rather than remaining inside the building and causing moisture damage, mold growth, and other associated problems. These building materials may also play a role in insulating the building. Finally, of course, it is desirable to have the materials available at a reasonable cost.
Roofing underpayment is a sheet-like material secured to the framing of the roof to provide a protective barrier before the final roofing materials (shingles, tiles, etc.) are installed. Roofing underpayment should be sufficiently impermeable to air and liquids to protect the interior of the house from wind, rain or other precipitation during construction. On the other hand, it may be desirable to have roofing underpayment that is breathable, which will allow water vapor to escape through the roofing underpayment to prevent such problems as water damage, the growth of molds, or the like. Further, roofing underpayment should have adequate tensile and physical properties such as break strength, elongation, tear strength, shrink resistance, and puncture strength to avoid damage during installation and to facilitate durability.
There are two typical methods of constructing roofs in the United States. In one method, a deck of plywood is laid down over the rafters, the roofing underpayment is placed over the deck, and the final roofing materials, such as shingles, are installed over the underpayment. In the other method, no deck is laid down over the rafters; rather, the roofing underpayment itself must be able to support the weight of the roofing material and the roofer who is installing the roof.
Traditionally, an asphalted felt material has been used for roofing underpayment. This material has the advantage of being waterproof. Asphalted felt has acceptable tensile and tear strength, but is known to be prone to tearing during high-wind weather conditions. Unfortunately, asphalted felt ages with heat and tends to pick up moisture, both of which result in the asphalted felt degrading over time. Asphalted felt is also very heavy and hence very difficult to lift onto a roof. Thus, the underpayment must be installed in multiple ‘patches’ because the weight of the material limits the size of roofing underpayment rolls.
Recently, underpayment comprising polymer films laminated to fabrics or scrims has been introduced to the market. These materials are substantially lighter than the asphalted felt materials, and hence are easier and more convenient to maneuver and install. However, these materials tend to be slippery, especially when they are wet, which creates a slip hazard for the roofer who is doing the installation.
Accordingly, a need exists for improved moisture-resistant materials for B&C applications which are light, easy to install, and with improved wet slip resistance.